by Chetan Nayak, Technical Fellow and Corporate Vice President of Quantum Hardware
Quantum computers have the potential to revolutionize science and society, but they can only do so once they reach the scale once thought distant and ensure their reliability through quantum error correction. Today, we’re announcing significant progress on the path to practical quantum computing:
- Majorana 1: The world’s first Quantum Processing Unit (QPU) powered by a Topological Core, designed to scale to a million qubits on a single chip.
- A hardware-protected topological qubit: Research published today in Nature, along with data shared at the Station Q meeting, demonstrates our ability to leverage a new type of material and engineer a radically different qubit that is small, fast, and digitally controlled.
- A device roadmap to reliable quantum computation: Our progression from single-qubit devices to arrays that enable quantum error correction.
- Building the world’s first fault-tolerant prototype (FTP) based on topological qubits: Microsoft is on track to create an FTP of a scalable quantum computer within years, not decades, as part of the final phase of the Defense Advanced Research Projects Agency (DARPA) Underexplored Systems for Utility-Scale Quantum Computing (US2QC) program.
Together, these milestones represent a pivotal moment in quantum computing, transitioning from scientific exploration to technological innovation.
Harnessing a New Type of Material
Today’s announcements are built on our team’s recent breakthrough: the world’s first topoconductor. This groundbreaking class of materials allows us to create topological superconductivity, a new state of matter that was once only theoretical. This advancement is the result of Microsoft’s innovations in the design and fabrication of gate-defined devices that combine indium arsenide (a semiconductor) with aluminum (a superconductor). When cooled to near absolute zero and manipulated with magnetic fields, these devices form topological superconducting nanowires with Majorana Zero Modes (MZMs) at the ends of the wires.
For nearly a century, Majorana Zero Modes (MZMs) existed only in textbooks. Today, we can create and control them on demand using our topoconductors. These quasiparticles form the foundation of our qubits, storing quantum information through “parity”—whether the wire contains an even or odd number of electrons. In conventional superconductors, electrons form Cooper pairs and move without resistance, and any unpaired electron can be detected because it requires additional energy to exist. However, in our topoconductors, an unpaired electron is shared between two MZMs, making it invisible to the environment. This unique characteristic protects the quantum information, enhancing the stability of the qubit.
While topoconductors are ideal candidates for qubits, they pose a challenge: How can we measure quantum information that is so well hidden? Specifically, how can we differentiate between 1,000,000,000 and 1,000,000,001 electrons?
Our solution to this challenge works as follows:
- Coupling to Quantum Dots: We use digital switches to couple both ends of the nanowire to a quantum dot—a tiny semiconductor device capable of storing electrical charge.
- Change in Charge Holding: This connection increases the quantum dot’s ability to hold charge, with the exact increase depending on the nanowire’s parity (whether it’s even or odd).
- Microwave Reflection Measurement: We measure the change in charge holding using microwaves. The microwaves reflect off the quantum dot, carrying an imprint of the nanowire’s quantum state.
- Reliable Measurement: We’ve designed our devices so that these changes are large enough to be reliably measured in a single shot. Initial measurements showed a 1% error probability, and we’ve identified ways to significantly reduce this.
Our system demonstrates impressive stability. External energy sources, like electromagnetic radiation, can break Cooper pairs, creating unpaired electrons that may flip the qubit’s state from even to odd parity. However, our results show this occurs only once per millisecond on average, suggesting that the shielding surrounding our processor is highly effective at blocking radiation. We are actively exploring further ways to reduce this frequency.
While it’s expected that quantum computing would require engineering a new state of matter, what’s truly remarkable is the accuracy of our readout technique. It demonstrates that we are successfully harnessing this exotic state of matter for quantum computation.
Revolutionizing Quantum Control Through Digital Precision
This new readout technique also enables a radically different approach to quantum computing, where measurements are used to perform calculations.
Traditional quantum computing requires rotating quantum states through precise angles using complex analog control signals tailored to each qubit. This makes quantum error correction (QEC) difficult, as it depends on these sensitive operations to detect and correct errors.
Our measurement-based approach simplifies QEC significantly. We perform error correction entirely through measurements activated by simple digital pulses, which connect and disconnect quantum dots from nanowires. This digital control approach makes it far more practical to manage the large number of qubits required for real-world applications, making scalable quantum computing more achievable.
With the core building blocks now demonstrated—quantum information encoded in Majorana Zero Modes (MZMs), protected by topology, and processed through measurements—we are ready to transition from a physics breakthrough to practical implementation.
The next step is to develop a scalable architecture based around a single-qubit device called a tetron (see Figure 2). At the Station Q meeting, we shared data demonstrating the basic operation of this qubit. One fundamental operation—measuring the parity of one of the topological nanowires in a tetron—uses the same technique described in our Nature paper.
Another essential operation puts the qubit into a superposition of parity states. This is also achieved by microwave reflectometry measurement of a quantum dot, but in a different configuration. Here, we decouple the first quantum dot from the nanowire and connect a different dot to both nanowires at one end of the device. By performing two orthogonal Pauli measurements, Z and X, we’ve successfully demonstrated measurement-based control—a crucial milestone that paves the way for the next steps in our roadmap.
Our roadmap now leads systematically toward scalable quantum error correction (QEC). The upcoming steps involve a 4×2 tetron array. Initially, we will use a two-qubit subset to demonstrate entanglement and measurement-based braiding transformations. Then, using the entire eight-qubit array, we will implement quantum error detection on two logical qubits.
The inherent error protection of topological qubits simplifies QEC. Additionally, our custom QEC codes reduce overhead by roughly tenfold compared to previous state-of-the-art approaches. This dramatic reduction means that our scalable system can be built with fewer physical qubits and has the potential to run at a faster clock speed, accelerating the path to practical, large-scale quantum computing.
DARPA’s Recognition of Our Approach
The Defense Advanced Research Projects Agency (DARPA) has selected Microsoft as one of two companies to advance to the final phase of its rigorous Underexplored Systems for Utility-Scale Quantum Computing (US2QC) program, a key component of DARPA’s broader Quantum Benchmarking Initiative (QBI). This recognition validates Microsoft’s roadmap for developing a fault-tolerant quantum computer based on topological qubits.
The US2QC program and the QBI employ a comprehensive, rigorous approach to evaluating quantum systems capable of addressing problems beyond the reach of classical computers. To date, the program has brought together experts from DARPA, the Air Force Research Laboratory, Johns Hopkins University Applied Physics Laboratory, Los Alamos National Laboratory, Oak Ridge National Laboratory, and NASA Ames Research Center, working collaboratively to verify quantum hardware, software, and applications. Looking ahead, the broader Quantum Benchmarking Initiative will expand its engagement, involving an even larger network of experts in the testing and evaluation of quantum computers.
Microsoft’s inclusion in the final phase follows an earlier selection based on DARPA’s assessment that we have the potential to develop a utility-scale quantum computer within a reasonable timeframe. DARPA conducted a thorough evaluation of our architectural designs and engineering plans for a fault-tolerant quantum computer. As a result of this detailed analysis, Microsoft and DARPA have formalized an agreement to enter the final phase, during which we aim to build a fault-tolerant prototype based on topological qubits in just a few years—an essential acceleration toward achieving utility-scale quantum computing.
Unlocking Quantum’s Potential
Eighteen months ago, we outlined our roadmap to building a quantum supercomputer. Today, we’ve reached our second major milestone: the demonstration of the world’s first topological qubit. Furthermore, we’ve already integrated eight topological qubits onto a chip designed to eventually house one million.
A million-qubit quantum computer represents more than just a milestone—it’s a critical gateway to solving some of the world’s most complex challenges. Even the most advanced supercomputers today struggle to accurately simulate the quantum processes that govern the properties of materials vital for our future. However, quantum computing at this scale has the potential to revolutionize industries by enabling innovations like self-healing materials for infrastructure, advancements in sustainable agriculture, and safer chemical discovery. What today requires billions of dollars in experimental research could be achieved through quantum computation.
Our path to practical quantum computing is clear. The foundational technology is validated, and we are confident that our architecture is scalable. Our new agreement with DARPA underscores our commitment to continued progress toward our ultimate goal: creating a machine that will drive scientific breakthroughs and address real-world challenges. Stay tuned for further updates as we continue this exciting journey.
Stay informed about Microsoft’s quantum computing advancements:
- Listen to Dr. Chetan Nayak on the Microsoft Research Podcast as he discusses these groundbreaking developments.
- Explore our papers published in Nature and on arXiv.
- Join us in becoming quantum-ready.
- Read the Microsoft Source story about today’s news.
This content is sourced from https://azure.microsoft.com/en-us/blog/quantum/2025/02/19/microsoft-unveils-majorana-1-the-worlds-first-quantum-processor-powered-by-topological-qubits/
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